Cirrus-ci-docs: Support cron builds

[simonbrandhof]

Cron builds would allow to schedule the execution of a build on a specified branch, at fixed intervals, independently of whether any commits were pushed to the repository.
Configuring a cron build from cirrus-ci.com would require to define the interval (hourly, daily, weekly or a custom value) and the branch (by default the branch marked as "default" in GitHub should be used).

Cron builds send notifications as any other builds.

[cevich]

This also supports having a polling 'bot' which could then do maintenance tasks on a repository. For example, checking all open PRs for a 'new' keyword like: '/bot: rebuild images' :wink:

[dbolkensteyn]

Any update on this @fkorotkov ?

I'd also be interested in programmatically starting a build using the GraphQL API, and essentially use Cirrus CI as a layer of abstraction over the various backends it supports (GCE, GKE, Azure, MacStadium, etc.) - which is slightly related to this use-case.

[fkorotkov]

@dbolkensteyn there was some preparational work done but some other things need be done to make sure cron jobs are organically integrated with everything else. The idea will be to provide a way to specify when to trigger a particular task. There will be a few conditions/options that you can multi-choose from:

• regular push
• CRON config
• manual trigger
• changes to certain files
• changes to certain files in a different repository

And maybe some other in the future.

Could you please create a separate issue for GraphQL API to trigger a Build for a particular reposioty, branch and optional SHA?

[simonbrandhof]

For reference: #90

[gspencergoog]

Hey @fkorotkov, any update on this feature?

[RDIL]

Any feature requests that do not have the coming-soon label are on hold.

[fkorotkov]

This feature will come after #90 and #74. This feature is not that trivial to make at scalable (GCP even has it's own paid version)

[gspencergoog]

Thanks for the update. I never thought it was trivial. :-)

[fkorotkov]

Initially I though it is pretty simple but the more thoughts I put into it the more complicated it appears. 😅

[simonbrandhof]

@fkorotkov I don't know at all your constraints, so just FYI: https://cloud.google.com/scheduler/ is an interesting service from GCP.

[duckinator]

Thank you so much for adding this!